Filtration apparatus.



W. A. STEVENSON.

HLTRATION APPARATUS.

APPLICATION FILED NOV. 11. ms.

Patented Apr. 25,1916.

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FILTRATION APPARATUS.

APPLICATION FILED NOV. H. 1913.

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WILLIAM A. STEVENSON, OF FLORENCE, MASSACHUSETTS.

FILTRATION APPARATUS.

Specification of Letters Patent.

Patented Apr. 25, 191".

Application filed November 11, 1913. Serial No. 800,263.

useful improvements in filtering beds and is applicable to apparatus ofthe general type shown, for instance, in United States Letters PatentNo. 798,473, granted August 29, 1905, to William W. Wilson, and inUnitedStates Letters Patent N 0. 1069737, granted to me August 12, 1918, inboth of which patents there is shown a bed of filtering ma terial withinwhich is located a branched collector conduit for taking oil thefiltered water and producing a reverse flow of wash water during theoperation of cleaning the filter bed and air pipes for introducingcurrents of air through the filter bed to cooperate with the wash waterin opening up or loosening the filtering material, and agitating itduring the washing operation. My patent above identified discloses meansfor preventing the back flow of water into the air pipes, this meansincluding a supplemen tary water supply for filling the air pipes withwater at certain stages of the operation of cleaning the beds.

The present mvention is directed more particularly to blow-ofi meansassociated with the air pipes of a system closely corresponding to thoseabove mentioned and affords means for freeing the air pipe system ofsand or sediment, or other foreign material, which may have enteredeither with the incoming air or because of reverse flow from the filterbed. I

The accompanying drawings illustrate a filtering apparatus of thisgeneral type, in which- Figure 1 is a sectional elevation of the singleunit with its necessary adjuncts; Fig. 2 is a partial plan view of thesame; Fig. 3 is a partial section transverse to the view of Fig. 1 andshowing blow ofi tubes'connected to the ends of the air pipe branches;

and Figs. 4 and 5 are, respectively, a plan view and an elevation of amodified form wherein the air pipe branches are themselves used as theblow-off conduits.

Similar letters of reference indicate similar parts throughout theseveral views.

In the drawings the filtering basin A is provided with the collectorconduit for the filtered water consisting preferably of a main collectorpipe B and branches C supported upon suitable grouting a, the branches 0being further provided with a series of slitted collector tubes 0. Thesecollector tubes are protected by a layer of gravel d above which thelayer of sand 0 extends, the top of the sand bed being usually about 12inches below the water level.

"Water admitted into basin A from channel D through spreader valve E and1naintained at uniform height by float F passes down through the sandand gravel to collector pipes C and B to a rate controller (ii anddischarges into the clear well H. A valve I in the connection to therate controller may be used to interrupt the fiow of Water when thefilter bed is to be washed.

To supply filtered water for washing the filter bed and removing thethin layer of slime which may collect on the sand, a con.- duit J isprovided having a cut-off valve and connected to the ,7 collector pipe Band its branches, so that by closing valve 1 near the rate controllerand opening the valve in con duit J, filtered water may be forced outunder pressure into all of the branches of the collector pipe andthrough the strainers attached to the collector pipe and its branchesand up through the sand, where the water will overflow into the wastewater channels K which are provided with sand intercepting side boards 7with air releasing tubes g. This upward How of wash water loosens up thefiltering material. and as the water rises in the bed, the float Factuates the float valve E, thereby shutting off the supply of theunfiltered water to the basin. The rising water carrying with it thefine sediment that has been deposited in and upon the sand layeroverflows into the channels K, from which it is conducted to the seweror other point of discharge.

In connection with the supply of wash water to the filter bed, air underpressure is admitted through the main S and its 'valve 1',

of chamber A, suitable screw branches L, and thelaterals M,communicating with the said branches. These laterals are provided with alarge number of fine slots to permit the air to discharge through theentire area of the bed, and in issuing from these slots the air expandssomewhat, making the agitation energetic and greatly increasing theefiiciency of the washing process.

During filtration, inasmuch as the filtered water discharges through therate controller at a point below the sand bed, the suction caused bythis negative head tends to produce a vacuum in the slitted air pipes,so that unless some compensating provision is made the closing of thevalve I preparatory to opening the valve admitting the supply offiltered wash water under pressure from. the conduit J, would beaccompanied by an inru-sh of water from the bed of sand into the systemof air pipes before the filtered wash water supply could reach thefilter bed. Such an inrush of water into the air pipes would carry inwith it more or less fine sand from the filter bed, thereby obstructingthe pipes. To avoid this difficulty, means are provided for filling theair pipe system with water from a water pressure main, as R, providedwith a suitable cut-off which is opened to admit water to fill the airpipe system L and its laterals M immediately before the valve in thebranch leading to the rate controller is closed, so that the air pipes Lbeing already occupied with water, will not be subjected to any inflowfrom the filter bed. As soon as the supply of wash water reaches thefilter bed and begins its upward flow therethrough, the valve "r isclosed, thereby interrupting the flow ofwater into the air pipes fromthe water supply main R, and a valve 8 is opened, leading from the airpressure main S, thereby driving the water out of the air pipe L and itsbranches M and admitting into the filter bed a corre sponding number ofjets of air through the slitted openings of said pipe and its branches,which air, in conjunction with the wash water, opens up and loosensthe-filtering material, and the wash water passes over into channels Kcarrying with it the sediment and impurities until the cleaningoperation is finished. At any time during the operation of theapparatus, when for any reason it becomes desirable to free the airpipes from water, sand, sediment, or the like, this may be effectedreadily by blowing water or air through the pipes and out by way of theblow-off means now to be described. 7

In the construction shown in Figs. 1 2 and 3, the air pipes L whichsupplythe air laterals M are all dead ended near the walls caps Z beingprovided for that purpose,

and their branches M,

but running parallel with pipes L are a series of blow-ofi pipes L, eachof which runs through the front wall of the apparatus and is providedwith a valve a", through which material blown from the air pipes mayfind exit. The air laterals M enter the sides of the blow-off pipes L asshown in Fig. 3, and with this arrangement the pipes L form an effectivetrap to collect sand and sediment and to hold the same until it is blownout ward therefrom through valve :1: by means of air or water suppliedunder pressure through pipe S.

In the modification illustrated by Figs. 4 and 5, each of the air pipesL is made to serve as its own blow-off pipe, and to this end isprojected forwardly through the front end of the apparatus and providedwitli a valve z which normally is closed, but which can be opened whendesiredi In this modification the air laterals lVI enter the sides ofpipes L instead of being dropped down with a T fitting, as in theconstruction "of Fig. 3, thereby forming a. collecting trap of each pipeL and making it serve the (1011-,

ble function of an air blow-off pipe.

With either of the constructions above described, the valves in or y canbe opened in succession or one can be opened simultancou sly withanother of the series, and the cleaning air or water can therefore bediverted or switched about through the system from tube to tube, thuscleaning not only the blow-off pipes L of Fig. 3 and L of Fig. 5, butalso effectively cleaning the air laterals M.

After cleaning the filter bed by reversing the flow of water through it,as above disclosed, accompanied by the forcible delivery of air upwardthrough the bed, the apparatus may be returned to normal filteringcondition, as follows: First. the cock .9 in the air pressure main S isclosed before the valve in the branch leading to the rate con-. trolleris opened. and before the valve in the conduit J admitting the washwater is closed. As soon as the valve .9 is closed, the valve r in thewater supply main R is opened and the filtered water from the supplymain R drives out the air from air pipe L and its branches M, said airrising with the wash water and making its exit from the filter. Thevalve in the wash water conduit J may then be closed and the valve inthe branch leading to the rate controller may be opened to reestablishfiltration, whereupon the pipe R in the water supply main is againclosed.

Other details of the apparatus may be as described in my Patent No.1069737, above mentioned, and may be operated in the manner and for thepurposes therein set forth. Certain features of the apparatus hereindisclosed, but not claimed, are claimed in my co-pending applicationSerial No, 782797,

supply pipe and a 1,180,618 will;

filedv August 4, 1913, as a division of the application which matured asPatent No. 1069737.

Having thus described my invention what I claim is:

l. A filtration apparatus having a filter bed, a conduit systemcontained in said filter bed for collecting the filtered water and forwashing the filter bed by a reverse flow, a conduit system includinglaterals for assisting the washing operation by the admission of airinto the filter bed during the reverse flow said laterals beingconnected so as to receive air at either end while in action andblow-oil means for said air system leading through the wall of thefilter bed whereby the pipes of said air system may be cleaned;substantially as described.

2. A filtration apparatus having a filter bed, a conduit systemcontained in said filter bed for collecting the filtered water and forwashing the filter bed by a reverse flow, the said system being providedwith a discharge pipe whose outlet is below the filter bed so as toestablish suction by a negative head during the filtration, an airconduit system including laterals for the admission of air into thefilter bed during the reverse flow said laterals being arrangedtoreceive air through either end and outlets for the air system throughthe wall of the filter bed whereby the air system may be blown out toclear the laterals and their associated pipes of foreign material;substantially as described.

3. A filtration apparatus having a filter bed, a conduit systemcontained in said filter bed for collecting the filtered water and forwashing the filter bed by a reverse flow, the said system being providedwith a discharge pipe whose outlet is below the filter bed so as toestablish suction by a negative head during the filtration, a conduitsystem including laterals for assisting the washing operation by theadmission of air into the filter bed during the reverse flow, saidlaterals being connected so as to receive air at either end while inaction, a water supply pipe connecting with the air conduit system, andmeans leading from said air conduit system outward from the filter bed,through which foreign material collecting in the laterals and in otherparts of the air conduit system may be blown out; substantially asdescribed.

A filtration apparatus having a filter bed, a conduit system containedin said filter bed for collecting the filtered water and for washing thefilter bed by a reverse flow, an air conduit system including lateralsfor assisting the washing operation by the admission of air into thefilter bed during the reverse flow, and auxiliary pipes leading from theends of said laterals through the wall of the filter bed, through whichpipes the laterals and other parts of the air conduit system may beblown off to free the system from foreign material; substantially asdescribed.

5. A filtration apparatus having a filter bed, a conduit systemcontained in said filter bed for collecting the filtered water and forwashing the filter bed by a reverse flow, the said system being providedwith a discharge pipe whose outlet is below the filter bed so as toestablish suction by a negative head during the filtration, an airconduit system with laterals free from deadends for assisting thewashing operation by the admission of air into the filter bed during thereverse flow and blow-0E pipes communicating with said air conduitsystem and leading outward from the laterals of the filter bed, saidblow-off pipes being valvecontrolled to provide for the eXit therethrough of material to be removed from the air conduit system;substantially as described.

6. A filtering apparatus having a filter bed, a conduit system containedin said filtering bed for collecting the filtered water and for washingthe filter bed by a reverse flow, a second conduit system contained insaid filtering bed for assisting the washing operation by the admissionof fluid into the filter bed, said second conduit system comprising aplurality of pipes and a plurality of laterals communicating therewith,said laterals each communicating at its ends with a pair of said pipes,said second conduit system being provided with blow-0H outlets extendingthrough the wall of said filter bed, and valves for opening and closingsaid blowofi' outlets, whereby when said valves are closed said secondconduit system is adapted to be used to assist in washing the filter bedand when said valves are opened said second conduit system may becleaned.

In testimony whereof I affix my signature, in presence of two witnesses.

WILLIAM A. STEVENSON.

Witnesses K. R. POWERS, F. H. BOYNTON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

